AcidBase
Worksheet #7 
Polyatomic
Acids & Bases 
1. 
Phosphorus acid, H_{3}PO_{4}, is actually a diprotic
acid; K_{a1} = 1.0 X 10^{2} and K_{a2 }= 2.6
X 10^{7}. What are the values of [H^{+}], pH and HPO_{3}^{2}
in a 1.0 M solution?

2. 
Tellurium, in the same family as sulphur, forms an acid analogous
to sulphuric acid and called telluric acid. It exists, however, as H_{6}TeO_{6}
(which looks like H_{2}TeO_{4} + 2 H_{2}O). It is
a diprotic acid. K_{a1} = 2.1 X 10^{8} and K_{a2}
= 6.5 X 10^{12}. Calculate [H^{+}], pH, and [H_{4}TeO_{6}^{2}]
in a 0.25 M solution of H_{6}TeO_{6}.

3. 
How many millilitres of 0.05 M phosphoric acid will be required
for reaction with 50 mL of 0.50 M KOH to yield a) KH_{2}PO_{4},
b) K_{2}HPO_{4}, c) K_{3}PO_{4}?

4. 
Write formulas for the primary, secondary, and tertiary lithium
salts of H_{3}PO_{4}. Write equations for the equilibria present
in an aqueous solution of a) H_{2}SO_{4}, b) H_{3}PO_{4}. 